From 03f9bb5d38a3855ee56087b9132f8ebbe13be747 Mon Sep 17 00:00:00 2001
From: Chris Dodge <cdodge@edx.org>
Date: Wed, 27 Mar 2013 22:37:07 -0400
Subject: [PATCH] use a request-scoped cache to keep the metadata inheritence
 tree around for the whole request. This means we should only do one trip to
 Memcached/Mongo per course per request. This is expected to keep memory
 utilization down

---
 common/djangoapps/request_cache/__init__.py   |  0
 common/djangoapps/request_cache/middleware.py | 20 +++++++++++++++++++
 2 files changed, 20 insertions(+)
 create mode 100644 common/djangoapps/request_cache/__init__.py
 create mode 100644 common/djangoapps/request_cache/middleware.py

diff --git a/common/djangoapps/request_cache/__init__.py b/common/djangoapps/request_cache/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/common/djangoapps/request_cache/middleware.py b/common/djangoapps/request_cache/middleware.py
new file mode 100644
index 0000000000..9d3dffdf27
--- /dev/null
+++ b/common/djangoapps/request_cache/middleware.py
@@ -0,0 +1,20 @@
+import threading
+
+_request_cache_threadlocal = threading.local()
+_request_cache_threadlocal.data = {}
+
+class RequestCache(object):
+    @classmethod
+    def get_request_cache(cls):
+        return _request_cache_threadlocal
+            
+    def clear_request_cache(self):
+        _request_cache_threadlocal.data = {}
+
+    def process_request(self, request):
+        self.clear_request_cache()
+        return None
+
+    def process_response(self, request, response):
+        self.clear_request_cache()
+        return response
\ No newline at end of file